In the past, image forming unit in an image forming apparatus such as electronic photography printer and the like, as disclosed in Patent Document 1 stated below, is composed of a toner cartridge which has a stirring member for stirring toner being filled in; a toner accommodating room to accommodate toner supplied from the toner cartridge; a supplying roller; a developing roller; a developing blade; a photosensitive drum; a charging roller; a exposing unit and the like. Here, the developing roller is furnished as contacting with and pressing the supplying roller. Further, the developing blade is furnished as contacting with the surface of the developing roller.    Patent Document 1: Japan patent publication of No. 2006-047470.
In the image forming unit, the stirring member is used for preventing grittiness of toner image caused by unevenness of granular distribution of toner filled in the toner cartridge; and for keeping fluidity so that toner does not solidify.
Then, through a control of a controlling section of the image forming apparatus, when the surface of the photosensitive drum is charged by using the charging roller, the exposing unit exposes print area on the basis of image data stored in memory. Thereby, on the surface of the photosensitive drum, an electrostatic latent image is formed which has an exposed exposure area where surface electric potential has lost by discharging electricity and a non-exposure area in charging state.
After the electrostatic latent image is formed on the surface of the photosensitive drum, through a control of the controlling section, toner being accommodated in the toner accommodating room and approaching the supplying roller adheres to the surface of the supplying roller. Then, the toner adhering to the surface of the supplying roller is pressed on a pressing and contacting area with the developing roller, takes a charge due to friction, and electrically adheres to the surface of the developing roller through Coulomb force of electric charge. The toner adhering to the surface of the developing roller, after passed the blade, becomes thin layer through a pressing and contacting force of the developing blade to regulate thickness of toner layer.
On the developing roller, a direct current voltage called developing bias is provided, the exposure area of the image forming unit formed on the photosensitive drum has lost surface electric potential. Therefore, an electric potential difference is generated between the surface of the developing roller and the exposure area of the electrostatic latent image formed on the surface of the photosensitive drum. By the electric potential difference, the toner adhering to the surface of the developing roller moves to the exposure area of the electrostatic latent image on the surface of the photosensitive drum.
After the toner moved to the exposure area of the electrostatic latent image on the surface of the photosensitive drum, a toner image is formed on the surface of the photosensitive drum as an visible image. Then, the toner image formed on the surface of the photosensitive drum is transferred onto print medium which is conveyed and is pressed on the photosensitive drum, by a transferring roller which is furnished to press and contact with the photosensitive drum.
In the image forming unit, a part of the toner that gets pressure from the supplying roller and the developing roller and is supplied to the surface of the developing roller, as development remainder toner, is not supplied to the surface of the photosensitive drum but is remaining on the surface of the developing roller. The development remainder toner is removed by pressure of the supplying roller in the pressing and contacting area of the developing roller and the supplying roller, and is accommodated to the toner accommodating room, then is used again in developing process.
However, in such image forming unit, it is impossible to obtain toner image with good quality, so that image quality becomes worse.